1. Field of the Invention
The present invention relates generally to ductwork for heating, ventilating and air conditioning (“HVAC”) systems, and in particular to a sleeve for protecting a length of flexible hose from crimping.
2. Description of the Prior Art
Hoses, ducts and conduits in various sizes and configurations are commonly utilized for conveying, routing and directing various substances and objects. In dynamic systems, examples of such substances include air which has been heated or cooled by heating and air conditioning equipment. In the construction industry such systems are commonly referred to as heating, ventilating and air conditioning (HVAC) systems.
Typical HVAC systems include runs of ductwork extending from the heating and air conditioning equipment to additional air handling equipment, or to distribution devices. Additional air handling equipment examples include variable air volume (“VAV”) boxes which are located in plenum spaces in many commercial structures. Heated and cooled air is typically introduced into the occupied spaces of buildings by diffusers which direct the airflow in predetermined distribution patterns for maximizing the comfort of the occupants.
Routing ductwork from the air conditioning and heating equipment to the supply diffusers often involves ducting routes which turn, bend and intersect with various components and with other runs of ductwork. To accommodate such curved, angled, and bent routing, flexible duct is commonly used for the final portions of the duct runs, which terminate at diffusers or other components. Flexible duct also has the advantage of being easily reconfigurable to accommodate changed space configurations and the like. Another advantage of flexible duct is that it is available with insulation to avoid condensation during cooling operation.
However, a disadvantage of flexible duct is that it tends to crimp when bent (FIGS. 5a, 6a and 7a). For example, 90° turns into diffusers can crimp unprotected flexible ducts. Crimping tends to restrict air flow and lower overall system efficiency. HVAC equipment thus works harder and consumes more power to overcome flow resistance associated with crimped flexible ducts.
A prior art solution to the problem of flexible duct crimping at diffusers and other bending locations is to install metal elbows, as shown in FIG. 7b. However, such additional components involve additional labor and material costs. Also, insulation may be required and further increase the installation costs.
The present invention addresses these disadvantages of prior art flexible duct installations. Heretofore there has not been available a sleeve for flexible duct with the advantages and features of the present invention.